python-stdnum commit: r116 - in python-stdnum: . stdnum stdnum/lv tests

[Commits of the python-stdnum project <python-stdnum-commits [at] lists.arthurdejong.org>]

Author: arthur
Date: Sat Feb 11 21:09:06 2012
New Revision: 116
URL: http://arthurdejong.org/viewvc/python-stdnum?revision=116&view=revision

Log:
add a PVN (Pievienotās vērtības nodokļa, Latvian VAT number) module

Added:
   python-stdnum/stdnum/lv/
   python-stdnum/stdnum/lv/__init__.py
   python-stdnum/stdnum/lv/pvn.py
Modified:
   python-stdnum/README
   python-stdnum/stdnum/__init__.py
   python-stdnum/tests/test_robustness.doctest

Modified: python-stdnum/README
==============================================================================
--- python-stdnum/README        Sat Feb 11 15:50:11 2012        (r115)
+++ python-stdnum/README        Sat Feb 11 21:09:06 2012        (r116)
@@ -33,6 +33,7 @@
  * FPA, ΦΠΑ (Foros Prostithemenis Aksias, the Greek VAT number)
  * Ust ID Nr. (Umsatzsteur Identifikationnummer, the German VAT number)
  * BTW, TVA, NWSt (Belgian VAT number)
+ * PVN (Pievienotās vērtības nodokļa, Latvian VAT number)
  * IMEI (International Mobile Equipment Identity)
  * IMSI (International Mobile Subscriber Identity)
  * MEID (Mobile Equipment Identifier)

Modified: python-stdnum/stdnum/__init__.py
==============================================================================
--- python-stdnum/stdnum/__init__.py    Sat Feb 11 15:50:11 2012        (r115)
+++ python-stdnum/stdnum/__init__.py    Sat Feb 11 21:09:06 2012        (r116)
@@ -47,6 +47,7 @@
  * FPA, ΦΠΑ (Foros Prostithemenis Aksias, the Greek VAT number)
  * Ust ID Nr. (Umsatzsteur Identifikationnummer, the German VAT number)
  * BTW, TVA, NWSt (Belgian VAT number)
+ * PVN (Pievienotās vērtības nodokļa, Latvian VAT number)
  * IMEI (International Mobile Equipment Identity)
  * IMSI (International Mobile Subscriber Identity)
  * MEID (Mobile Equipment Identifier)

Added: python-stdnum/stdnum/lv/__init__.py
==============================================================================

Added: python-stdnum/stdnum/lv/pvn.py
==============================================================================
--- /dev/null   00:00:00 1970   (empty, because file is newly added)
+++ python-stdnum/stdnum/lv/pvn.py      Sat Feb 11 21:09:06 2012        (r116)
@@ -0,0 +1,103 @@
+# pvn.py - functions for handling Latvian PVN (VAT) numbers
+# coding: utf-8
+#
+# Copyright (C) 2012 Arthur de Jong
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301 USA
+
+"""Module for handling Latvian PVN (Pievienotās vērtības nodokļa, VAT)
+numbers.
+
+It is a 11 digit number that can either be a reference to a legal entity
+(in which case the first digit > 3) or a natural person (in which case it
+should be the same as the personal code (personas kods)). Personal codes
+start with 6 digits to denote the birth date in the form ddmmyy.
+
+>>> compact('LV 4000 3521 600')
+'40003521600'
+>>> is_valid('40003521600')
+True
+>>> is_valid('40003521601')  # invalid check digit
+False
+>>> is_valid('161175-19997')  # personal code
+True
+>>> is_valid('161375-19997')  # invalid date
+False
+"""
+
+import datetime
+
+from stdnum.util import clean
+
+
+# validation functions are available on-line but it is not allowed
+# to perform automated queries:
+# http://www6.vid.gov.lv/VID_PDB?aspxerrorpath=/vid_pdb/pvn.asp
+
+
+def compact(number):
+    """Convert the number to the minimal representation. This strips the
+    number of any valid separators and removes surrounding whitespace."""
+    number = clean(number, ' -').upper().strip()
+    if number.startswith('LV'):
+        number = number[2:]
+    return number
+
+
+def checksum(number):
+    """Calculate the checksum for legal entities."""
+    weights = (9, 1, 4, 8, 3, 10, 2, 5, 7, 6, 1)
+    return sum(weights[i] * int(n) for i, n in enumerate(number)) % 11
+
+
+def calc_check_digit_pers(number):
+    """Calculate the check digit for personal codes. The number passed
+    should not have the check digit included."""
+    # note that this algorithm has not been confirmed by an independent source
+    weights = (10, 5, 8, 4, 2, 1, 6, 3, 7, 9)
+    check = 1 + sum(weights[i] * int(n) for i, n in enumerate(number))
+    return str(check % 11 % 10)
+
+
+def get_birth_date(number):
+    """Split the date parts from the number and return the birth date."""
+    day = int(number[0:2])
+    month = int(number[2:4])
+    year = int(number[4:6])
+    year += 1800 + int(number[6]) * 100
+    return datetime.date(year, month, day)
+
+
+def is_valid(number):
+    """Checks to see if the number provided is a valid VAT number. This checks
+    the length, formatting and check digit."""
+    try:
+        number = compact(number)
+    except:
+        return False
+    if len(number) != 11 or not number.isdigit():
+        return False
+    if number[0] > '3':
+        # legal entity
+        return checksum(number) == 3
+    else:
+        # natural resident, check if birth date is valid
+        try:
+            birth_date = get_birth_date(number)
+            # TODO: check that the birth date is not in the future
+        except ValueError, e:
+            return False
+        return calc_check_digit_pers(number[:-1]) == number[-1]

Modified: python-stdnum/tests/test_robustness.doctest
==============================================================================
--- python-stdnum/tests/test_robustness.doctest Sat Feb 11 15:50:11 2012        
(r115)
+++ python-stdnum/tests/test_robustness.doctest Sat Feb 11 21:09:06 2012        
(r116)
@@ -35,6 +35,7 @@
 >>> from stdnum.fr import siren
 >>> from stdnum.gr import vat as gr_vat
 >>> from stdnum.iso7064 import mod_11_10, mod_11_2, mod_37_2, mod_37_36, 
 >>> mod_97_10
+>>> from stdnum.lv import pvn
 >>> from stdnum.nl import bsn, onderwijsnummer, btw
 >>> from stdnum.us import ssn
 
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